linux - Which files are run when I log into or reboot my machine?

I'm trying to figure out which "script" (really it's probably an "*rc" file) is running a particular command when I reboot my ubuntu machine. I've tried grepping for what is being displayed when I log into the machine after a reboot but I haven't been able to find it.

I know that, for example, the .bash_profile is "sourced" when I log in but what others are run This will help me track down the script/file that's running an old set of commands that I need to update.

Thanks!

here's what happens when i log in:

bos-mp2o6:~ user$ ssh -A X.X.X.X
user@X.X.X.X's password: 
Linux bos-lpwy9 2.6.32-54-generic #116-Ubuntu SMP Tue Nov 12 19:23:22 UTC 2013 x86_64 GNU/Linux
Ubuntu 10.04.4 LTS

Welcome to Ubuntu!
 * Documentation:  https://help.ubuntu.com/

New release 'precise' available.
Run 'do-release-upgrade' to upgrade to it.

Last login: Tue Dec 31 10:53:25 2013 from 172.19.43.138
Agent pid 2117
/home/user/.ssh/internal/2013-07-29: No such file or directory
/home/user/.ssh/deployed/2013-07-29: No such file or directory
Identity added: /home/user/.ssh/external/2013-07-29 (/home/user/.ssh/external/2013-07-29)

if you notice the "Identity added" piece, that's the bit I'm looking for. So I've used the following command (with no luck):

[user@Linux_Desktop:~]$grep_bash 2013-07-29
[user@Linux_Desktop:~]$

Answer

This will depend on many things. I am guessing that you don't actually want the files run when the machine reboots (there are MANY) but those run by your shell (e.g. bash) when you log in or open a terminal.

The easiest way to find the relevant command would be to grep through all possible shell startup files, both for login and interactive shells. I have the following function defined in my $HOME/.bashrc:

grep_bash(){
  for f in  ~/.bashrc ~/.profile ~/.bash_profile ~/.bash_login \
        /etc/profile /etc/bash.bashrc /etc/environment; 
  do 
    [ -e $f ] && grep -H "$@" $f; 
  done
}

I can then use it to search those files for a string of interest:

$ grep_bash foo
/home/terdon/.bashrc:echo foo

---

The actual files being read depend on the kind of shell you are running. These are the relevant sections from man bash:

   When  bash is invoked as an interactive login shell, or as a non-inter‐
   active shell with the --login option, it first reads and executes  com‐
   mands  from  the file /etc/profile, if that file exists.  After reading
   that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile,
   in  that order, and reads and executes commands from the first one that
   exists and is readable. 

   When an interactive shell that is not a login shell  is  started,  bash
   reads  and  executes  commands  from /etc/bash.bashrc and ~/.bashrc, if
   these files exist.  This may be inhibited by using the  --norc  option.
   The  --rcfile  file option will force bash to read and execute commands
   from file instead of /etc/bash.bashrc and ~/.bashrc.

In most *nix (the only exception I know of is OSX) the default shell when you open a new terminal is an interactive, non-login shell so ~/.bashrc and company are read.

Finally, you also have /etc/environment which is used to set global environment variables and which should be read by most shells.

---

After discussion with the OP in chat, @derobert helped us figure out that the issue here was caused by /etc/ssh/sshrc.